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Extreme high temperatures are occurring more frequently with ongoing anthropogenic climate warming, but the experimental tests of the effects of high temperatures on terrestrial vertebrates in natural conditions are rare. In this study, we investigated the effects of extreme high temperatures on female reproduction and offspring traits of multi-ocellated racerunners (Eremias multiocellata) kept in field enclosures in the desert steppe of Inner Mongolia. Our studies indicate that high temperatures significantly affect the gestation period and reproductive output of females and the offspring sex ratio, but have little impact on offspring body size and mass. More interestingly, we found that the effect of extreme high temperatures on female reproductive output was not consistent between two consecutive years that differed in precipitation. Low precipitation may aggravate the impact of climate warming on lizards and negatively affect the survival of lizards in the desert steppe. Our results provide evidence that temperature interacts with precipitation to determine the life history of lizards, and they suggest that a drier and hotter environment, such as the future climate in arid mid-latitude areas, will likely impose severe pressure on lizard populations, which are an important component of the food web in desert areas around the world.

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The sex determination mechanism for the Chinese soft-shelled turtle (Pelodiscus sinensis) is subject to controversy. Some populations have been shown to possess sex chromosomes and thus genotypic sex determination (GSD), while others were reported to exhibit temperature-dependent sex determination (TSD). To test whether TSD and GSD coexist in this species or whether populations differ in their sex-determining system, we conducted egg incubation experiments to investigate how temperature influences hatchling sex in a wide range of populations of this species in China. In parallel, we used comparative genome hybridization (CGH) to study the micro-sex chromosomes of adult P. sinensis in the 2 populations that were previously identified to be TSD. The incubation experiments showed that temperature did not affect hatchling sex in any of the studied populations. CGH indicated that turtles have micro-sex chromosomes of the female heterogametic (ZZ/ZW) system in the 2 disputed populations. These results indicate that P. sinensis is a GSD rather than a TSD species. Thus, the apparent coexistence of TSD and GSD in this species is the result of previous misdiagnosis in purportedly TSD populations.

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